Heat transfer apparatus



Nov. 27, 1934. D. R. M NEAL.

HEAT TRANSFER APPARATUS Filed April 16, 1932 2 Sheets-Sheet 1 lllllllllllllllll I VENTOR ATTORNEYS.

NOV. 27, 1934. R, MCNEAL HEAT TRANSFER APPARATUS Filed April 16, 1952 2Sheets-Sheet 2 a INV%TOR f-Mwu ATTORN EYS.

Patented Nov. 27, 1934 iJNITED STATES lPAiTEN'i" FFICE Appiication April16, 1932, Serial No. 605,618

3 Claims.

This invention relates to heat transfer apparatus and is especiallyconcerned with aftercooler apparatus for cooling air or any other gas,

particularly under pressure.

The general objects of the invention have reference to improvedefliciency, construction of the parts in such manner as to greatlyincrease their life' and provision of cooling apparatus which is notonly simple and inexpensive in manufacture but which is, furthermore,readily inspected, re-- paired or the like.

To consider some of the more or less detailed objects and advantages, itshould first be noted that at least certain features of the inventionare especially useful for cooling air or other gas under pressure. Anair or gas compressor ordinarily results in a substantial increase inthe temperature of the air or gas. For many reasons which need not beconsidered in detail herein,

1 it is desirable, either before storage or before use,

or both, that the temperature of the gas or air be decreased or lowered.Such cooling is also, at least in many instances, preferably effected ata point relatively close to the compressor. However, the action of thecompressor results, among other things, in irregularities in pressure orpulsations of the gas. Such pulsa ions, especially where they aresubstantially constant throughout the use of the apparatus, haveheretofore produced vibrations in the cooling apparatus and as aconsequence, parts of the cooler have become worn or shaken loose sothat breakdown or leakage results.

It is an important object of this invention to construct an air or gascooler of a type capable of withstanding vibrations or the like. Theparticular manner in which the foregoing is accomplished will appearmore fully hereinafter, it being merely noted at this point that theinvention has in View materially increasing the life of the coolerparts, especially with respect to wear and leakage encounteredheretofore as a result of vibrations set up by the compressor.

Another problem in connection with the foregoing should also beconsidered at this point. In

' Fahrenheit or even higher, and this high temperature air, togetherwith oil vapors in the receiver, has resulted in explosions of a veryserious character.

However, in accordance with ,the arrangements of the prior art, it hasnot been practical'to locate the air cooler closely adjacent to thecompressor (for example, between the compressor and the receiver) forthe reason that the pulsations resulted in excessive vibration andresultant wear on various parts of the coolers employed. Thus, inaccordance with this invention, I contemplate the interposition of anair cooler between the compressor and the receiver.

Ordinarily, moisture and vapor separators operate only veryinefliciently under pulsating pressure conditions. However, since thecooler of this invention serves to minimize or very greatly reduce theforce of the pulsations, I am enabled to employ a separator in theconnection between the compressor and the receiver. This separator, aswill be explained more fully hereinafter, is preferably associateddirectly with the cooler to constitute a unitary part thereof. Theadvantage of such an arrangement, of course, resides in the fact that alarge quantity of the oil and water vapors are condensed during coolingof the air and thus never even enter the receiver tank. With the reducedquantity of oil and water vapor and condensate in the receiver tank, andwith the very substantially lowered temperature of the air before itsentry into the receiver, the possibility of explosion is practicallyeliminated.

How the foregoing and other objects and advantages are obtained will beapparent from a consideration of the following description makingreference to the accompanying drawings, in which Figure 1 is a somewhatdiagrammatic side View of an air compressor and reservoir with thecooler of the present invention associated therewith;

Figure 2 is a longitudinal sectional view taken through the inlet end ofthe cooling apparatus;

Figure 3 is a view similar to Figure 2 but taken through the outlet endof the apparatus;

Figure 4 is a transverse sectional View taken substantially as indicatedby the section line 4-4 on Figure 3;

Figure 5 is a view showing a plurality of the cooling units of thisinvention associated in a particular manner to illustrate certaindesirable features thereof; and

Figure 6 is an elevational view illustrating the heat exchanger of thisinvention mounted in a generally horizontal position.

Referring first to Figure 1, a compressor is indicated by the referencenumeral 6, it being noted that the specific construction of thiscompressor need not be considered in detail herein since it forms no,part of the present invention per se. It might be noted, however, thatsuch a compressor ordinarily produces pulsations in the air or gas beingcompressed. The air reservoir or receiver is illustrated in Figure 1 at7 and is shown as being equipped with a discharge or supply pipe 8 andan inlet connection 9 between which and the discharge connection 10 ofthe compressor, the cooler, generally indicated at 11, is interposed.While the foregoing general arrangement of compressor, cooler andreceiver is particularly advantageous for reasons above brought out, itshould be understood that at least some advantages of theconstruction'of the cooler herein specifically disclosed may be obtainedby the arrangement of the several parts in other ways.

The cooler 11 (see Figures 1, 2 and 3) includes an elongated cylinderorshell 12 having, at one end thereof, a header or connection device 13.This header constitutes the inlet means for the cooler and is providedwith a pipe connection or nipple 14 extended transversely of the shell12.

Airor gas tubes 15 are extended lengthwise through the shell 12 andterminate, toward the inlet end, in a tube sheet 16 which mayconveniently be secured in position between shoulder 17 formed on theheader 13 and shoulder 18 arranged at the end of, the casing or shell12. Suitable packings or packing rings 19 may be interposed between thetube sheet and the shoulders 17 and 18 and these several parts arerigidly secured to'each other as by means of bolts 20.

At their other ends, the tubes 15 terminate in a sheet 21 which isarranged for sliding movement inside the shell 12 in order to compensatefor relative expansion and contraction of the tubes and shell. At theoutlet end an additional header or connection device 22, having atransversely extended discharge nipple 23, is arranged for connection(in accordance with the layout of Figure 1) through pipe 24 with theinlet 9 of the reservoir 7. The inlet and outlet headers may thus besimilarly formed and they may conveniently be provided with closure orcover plates 25 and 26 arranged at opposite ends of the cooling unit.

In accordance with this invention, the several tubes 15 which constitutethe cooling elements are each belled outwardly at their ends asindicated at 15a in Figures 2 and 3, beyond the two tube sheets 16 and21. Thus the tubes together with their belled ends constitute generallyVenturi shaped passages, the advantages of which will be touched on morefully hereinafter.

While I may arrange the outlet or discharge header 22 immediatelyadjacent to one end of the shell 12, I prefer to interpose a gas or airdrying device, generally indicated at 27, between the end of the coolerproper and the discharge header 22.

As shown in Figure 3 the separator or drying device includes spiralvanes or baiiies 28 arranged to separate moisture and provide foraccumulation thereof in the chamber 29 to be withdrawn this invention itis conveniently associated with the cooling unit to constitute a partthereof. It

- is further observedthat in accordance with this arrangement theseparating chamber, in effect, constitutes a portion of the outlet ordischarge header.

The present invention further provides for the attachment of thedischarge header means (with or without the separator) directly to thetube sheet 21, bolts 31 or the like being provided for this purpose. Apacking ring or gasket 32 is interposed between the outer face of thetube sheet and the header part associated therewith. A packing deviceincluding a gland 33 and packing 34 is arranged between the shell orcasing 12 and the circumference of the tube sheet 21. Adjusting andtightening bolts 35 serve to maintain the proper joint between theseparts.

From the foregoing it will be seen that, in contradistinction to themore usual practice, this in- 12 and an outlet 37 1s provided adjacentthe other end. Thus the arrangement provides for counterflow of thecooling medium. The counterficw,

however, is not direct, since the invention further makes provision forthe use of a novel type of baffle means in the shell to cause thecooling medium to follow a substantially transverse path across portionsof the tubes. As will be seen in Figures 2, 3 and 4, the bafile meansinclude a series of parallel and spaced baffle elements 38 each of whichextends transversely or across sectionally of the casing 12. As clearlyseen in Figure 4, each baffle 38 is provided with a rounded edge at oneside thereof to conform to the inner surface of the shell 12. At theother side (the division line lying approximately along a diameter ofthe shell) each element 38 is cutaway, as indicated at 39, to provide asemi-annular passage 40 through which the cooling medium .may pass inits flow beyond each successive bafile. By reference to Figure 4 it willalso be seen that the tubes 15 are arranged in a cylindrical nest orbundle of such diameter as to leave a substantially unrestricted annularpassage or cavity just inside the casing 12. The several baffles 38 maybe spaced from each other as by means of the thimbles or sleeves 41threaded on one or a few of the tubes in the manner clearly shown inFigures 2, 3 and 4. In order to ensure passage of the cooling mediumbetween the tubes themselves rather than around the edges of the bundle,additional baffle elements 42 are extended lengthwise between the plates38, these additional bafiies also preferably being arranged atdiametrically opposite sides of the tube nest (see Figure 4) Withbafiies of the fore going type alternately disposed as shown in Fig ures2 and 3, the water or other cooling medium entering through the inlet 36first passes transversely across the tube nest and then upwardly (asviewed in Figure 3) beyond the cutaway-portion of the first baiiie 38.From this point the medium is again deflected in the opposite transversedirection for passage through the tubes and, as a result, the flow, ingeneral, is from one end of the casing 12 to the other, although themedium moves in a zigzag path during this gen-.

.Another feature of the invention involves the use of removable ordetachable supporting feetor brackets 43 (see Figures 1,.31and 6)arranged to cooperate alternatively with any one :of a :num-

er of attachment means 44 with which the easing l2'is provided.AssshownainFigures 1,?Brandi6 these attachment means 44 are provided :ation-- git-udinally as well .as radially ofiset :points and the brackets43 are so constructed that they may readily be securedto the casingatone endithere of only (for example, as shown in Figure :1 to sup portthe cooler in a vertical position) or one at each end thereof (forpurposes ofrsupport .a substantially horizontal position, as Shown inFigure 6) Before considering the operationof the apparatus thus fardescribed, .referenceshould :bermade to Figure 5 in which I haveillustrated a parallel arrangement or" a pair of cool ng units of thetype shown in Figures 11 to '4 inclusive. 'Withithls arrangement, theair supply line 1011 may .iconveniently be coupled. with the header 1311at one end of one unit and the discharge connection Zea may similarly beassociated with the header 13b of the other unit, .the two headers 13aand 13b just mentioned being located adjacent to each other. Similarly,at their other ends, the outlet headers 22a) and 22b may beinterconnected by the pipe l5. Thecooling medium .or water connectionsare similarly arranged and, as shown, include connection of the supplyline 46 with the inlet 37?), connectionof the discharge pipe 47 with theoutlet 37a and an interconnecting pipe 28 extended between theconnection means 36b and'36a.

In considering the operation, first of the arrangement illustrated inFigure 1, assume first that the compressor 6 is being employed todeliver air under pressure to the receiver 7. As noted above, thisaction results in irregular or pulsating pressure conditions in the airline. Heretofore, such pulsations have resulted in vibration or the likeof various portions of the cooling apparatus employed and thevibrations, in turn, have not infrequently producedbreakdowns or atleast difficulties with respect to leakage. Before proceeding furtherwith the operation of the particular cooler disclosed herein, "it shouldbe noted that heretofore the air has ordinarily been circulated around aplurality of tubes through which the cooling medium is passed. With sucharrangements the vibrations resulted in loosening of the tube joints inthe tube sheets I and further, where baffles were employed, thevibraiions resulted in cutting or wearing of the tubes at points wherethey passed through the baffles.

In the arrangement herein disclosed, which provides for the passage ofthe air or gas to be cooled through the tubes, rather than around them,and further with belled openings at each end of each tube, any tendencyto produce vibrations is practically eliminated. The cause of this maypossibly be involved in the Venturi action of the belled tubes or it maypossibly be because the water or other cooling medium surrounding tubesaids in damping out or absorbing the vibrations, or both. However,whatever may be the cause of the wear heretofore encountered, I havefound that by passing the air through the tubes and the cooling liquidaround the tubes by the means above described, wear of the tubes by thebafiles and loosening of the tubes in their supporting sheets is verymaterially reduced, so that, as a practical matter, these vibrations areno longer a'factor'in determining the life :of the cooler.

The reduction in vibration and wear also per-' mits the use of tubeswhich are not individually packed in the tubesheets. In the practice ofthe priorart, where the vibrations were likely to loosen the tubes intheir sheets, individual packings for the tubes have sometimes beenemployed. Individual packings, of course, necessitate a wider spacing ofthe tubes and also produce other obvious disadvantages.

As :an additional advantage which flows from the damping out of thevibrations or pulsations in the .air being cooled, it is observed thatthe condition of the air after it is discharged from the cooler properis such that a separator of the character above referred to may readilyand efliciently beemployed to remove condensed oil and water vapor.prior to entry of .the air into the receiver.

.Inaddition to the foregoing, in accordance with prior practice (thatis, where the air or gas to be cooled was circulated around the outsideor anest of tubes) it was necessary to employ various packing deviceswhich were subject to air or gas pressure. .Such packing devices werenecessarily employed between a'tube sheet and the casing of the coolerin order to permit relative movement thereof and thus compensate forexpansion and contraction. With the apparatus of this invention, themeans arranged to compensate for expansion and contraction requires apacking which is only subjected to the pressure of the cooling medium,this quite frequently being relatively low as compared to the highpressure of the gas or air often employed. An additional point to beconsidered is the fact that the cool ing medium isvusually a liquid anda packing device, of course, may be arranged for much more eflicientoperation to prevent leakage of a liquid than to prevent leakage of airorany othergas.

A further feature of importance resides in the use of an inlet headerhaving a connection extended thereto generally transversely of the extension of the cooling tubes. This will be apparent from inspection ofFigure 2 in which it will be seen that the incoming air, in making-theturn from the inlet nipple to the entrance ends of the tubes, will bevery uniformly distributed between the several tubes. The inletarrangement just referred to also cooperates with the belled ends of thetubes in reducing vibrations and the like.

The arrangement of the inlet and outlet headers for cooperation withtransversely extended connections is also of advantage in compensatingfor-expansion and contraction, because, during relative movement of thetwo headers (by expansion or contraction), the associated pipeconnections need only flex slightly transversely thereof and, as aresult, there will be no tendency to -cause buckling of the connectionsextended to the cooler.

The arrangement of the connections, furthermore, including :those forthe cooling medium, is also advantageous in facilitating mounting of thecooler in any desired position (usually vertica-lly or horizontally). Aswill also be apparent from inspection of Figure 5 the connectionarrangements, particularly the extension thereof u with respect to thelongitudinal axis of the cooler, are further such as to facilitatemounting of two or more of the coolers, it being noted that thisfacility is maintained even though the coolare are horizontally orvertically disposed. When a plurality of the units are arranged as inFig.- ure 5, the air and water line connections are not subject to anybending or buckling strains whatever during expansion and contraction,since'all of the necessary connections are associated with parts whichare relatively fixed. Thus, referring to Figure 5, the supportingelements 43 are arranged to support the casings of the cooler units, aswell as all the connections extended to and from the units, in a fixedposition, and when expansion and contraction takes place, the lower andinterconnected headers move up anddown with the lower tube sheets 21.

As an additional advantage, the cooler elements themselves, i. e., thenest of tubes with its associated tube sheets, may be removed from thecasing as a unit. In this way, the original construction, maintenance,inspection and repair are all materially facilitated, it being notedthat in order to remove the internal-elements, it is necessary only toremove nuts 31, remove the upper header (as viewed in Figures 2 and 3)and then pull out the nest of tubes with its associated tube sheets.Access to the interior of the tubes themselves may also be had by mereremoval of the end cover plates for the inlet and outlet headers.

The apparatus of this invention has further been found, by actual test,to effect a certain washing or cleansing of the air being cooled. Whilethe exact reasons for this are not all definitely known, at the sametime, experiments show that by the passage of the air to be cooledthrough a plurality of relatively small diameter tubes of the characterabove described, the tendency for dirt particles, dust and the like tocarbonize in the tubes is very materially reduced as compared to themarked tendency to carbonize where the air to be cooled is circulatedaround the exterior of a nest of tubes. ther shown that, with thevarious parts of the cooler arranged, for example, as shown in Figures1, 2 and 3, a very large percentage of the dust and dirt is removed withthe oil and water condensate in the separator.

ly in excess of that effected by other separator arrangements. In fact,the percentage of dirt removed is much greater than that effected by theuse of a separator, even substantially identical to the one shown, whenthe separator is located with other types of cooling apparatus or insome other relation with respect thereto.

Finally, it should be observed that while certain features of theinvention are particularly useful in the cooling of air under pressure,for reasons fully brought out above, at the same time, at least certainfeatures of the invention are equally applicable to heat exchangeapparatus for other purposes.

1. Gas or air heat transfer apparatus including anelongated cylindricalcasing adapted for the passage of a heat transfer medium therethroughgenerally from one end to the other end thereof, tubes extendedlengthwise through,

Experiment has fur- Indeed, the percentagev of dirt and the like removedin this way is greatthe casing for the gas or air between which and saidmedium the heat transfer is to be effected,

deflecting said medium in a transverse direction across portions of saidtubes, said bafiie means including plate-like elements of generallycircular shape having approximately one-half thereof dimensioned to fitthe interior curvature of the casing and having a semi-annularcutaway-portion at the other side thereof to provide for passage of themedium generally axially of the casing in the annular space between thenest of tubes and the internal casing wall, there being a plurality ofsuch plate-like elements arranged in spaced relation along the length ofthe casing with their cutaway-portions alternately oppositely disposedat different sides of the casing, together with additional bafflesextended between said plate-like elements and lying in planes disposedgenerally radially of the casing in the annular space between the innercasing wall and the nest of tubes, there being baffies of the type lastmentioned positioned at opposite sides of the casing adjacent the pointsof termination of said cutaway-portions of the plate-like elements.

2. In heat transfer apparatus an elongated tubular casing, heat transferelements in the casing extended generally lengthwise thereof, connectionmeans arranged toward opposite ends of the casing at oneside thereof,and means for supporting the. casing in either substantiab H ly uprightor substantially horizontal position,

the last means including a plurality of attachment means adapted tocooperate with supporting elements, the attachment means being car-'ried by the casing and spaced from each other thereon toward oppositeends of the casing and radially offset from said connection means,whereby said attachment means may alternatively be associated withdifferent supporting elements to provide for support of the casing insubstantially horizontal or substantially vertical position and at thesame time to maintain convenient access to the connection means for thepurpose of making connections to and from the heat transfer elements.

3. In heat transfer apparatus, an elongated l'.

tubular casing, heat transfer elements in the casing, and a mechanismfor supporting the casing in either one of at least two differentpositions, such mechanism including a plurality of supporting meanscarried on the casing, the supporting means being positioned at pointswhich are radially and axially offset from each other, whereby variousof the supporting means may alternatively be employed to cooperate withfixed supports spaced axially or circumferentially of I- the casing andthus provide for support of the casing in a generally horizontalposition or in a generally vertical position.

DANIEL RAYMOND MCNEAL.

